Rotary core barrel



' /N VENTOQ..

A TTORNEYS,

ROTARY CORE BARREL Filed June '7, 1953 R. C. BAKER ET AL March 19, 1935.

Patented Mar. 19, 1935 UNITED STATES PATENT OFFICE ROTARY CORE BARRELApplication June 7, 1933, serial No. 674,657

Claims.

This invention relates to oil well drilling equipment and particularlypertains to improvements in devices for taking samples of the formationpenetrated by rotary drilling equipment.

It is common practice in the drilling of oil wells to take a core of theformation to b e penetrated. This is accomplished by the use of a corebarrel which generally includes a pair of concentrically disposedybarrels, the outer being a l0 drill barrel and the inner one a coretube. In

operation, the cutter head carried by the drill barrel cuts an annulargroove, leaving intact a central core which is received by the corebarrel. The lower end of the core barrel is fitted with a trimmer shoeto trim the core prior to its entrance into the core tube. Inpenetrating comparatively hard formations it is desirable to have thecutter teeth in advance ofthe core tube. However, in soft formations itis desirable to have the core tube in advance of the cutter teeth inorder to eiect a maximum recovery and prevent loss of the core due tothe washing action of the circulating uid and disintegration thereof dueto the drilling action.

It is, therefore, the principal object of the present invention togenerally improve upon the construction of core barrels and to provide acore extractor that will effect a maximum core recovery of a well insoft or sandy formations as Well as in harder formations.

The object is attained by enabling the position of the lower end of thecore barrel to be changed in an axial direction relative to the cuttingteeth of the drill barrel so that in soft formations the lower end ofthe core tube may be positioned in advance of the drilling shoe and thusreceive and protect the core before it has been disrupted by the.drilling fluid and action of the cutter teeth and in hard formationsthe core tube may be positioned with the cutter teeth in advance thereofso that the core is formed by the cutter head and then received by thecore tube.

A further object of our invention is the provision of improved means formounting the core tube Within the drill barrel body which facilitatesthe ready removal of the core tube from the drill barrel after thecorephas been taken.

One form which the invention may assume is exemplied in the followingdescription and i1- lustrated by way of example in the accompanyingdrawing, in which:

Fig. 1 is a central vertical section of a rotary core barrel constructedin accordance with the invention and showing the core tube in a low-(Cl. Z55-72) ered position suitable for taking a core from soft or sandyformation.

Fig. 2 is a similar view showing the core barrel in its raised or normalposition for extracting a core from harder formations.

Fig. 3 is a section taken on the line Il1III of Fig. 4.

Fig. 4 is an enlarged fragmentary view partly in section illustratingthe construction of the thrust sub which permits easy removal of the l0core barrel from the drill barrel.

Referring more particularly to the drawing, a rotary core barrel isshown as comprising a drill barrel 10 which is tted at its lower endwith a threaded sleeve 11. This sleeve l1 is welded to 15 the drillbarrel body and receives a drilling shoe or cutter head 12 on its lowerthreaded end. The, cutter head 12 is provided with cutting teeth 13which upon rotation of the drill barrel cut an annular groove in theformation penetrated to form a core that may be Vextracted from the wellfor examination.

The upper end of the drill barrel body 10 is connected by welding orother suitable means with a sleeve 14 exteriorly threaded at its upperend for connection to a drill barrel sub 15, which sub has a threadedsocket for the reception of a drill stem 16 by means of which the corebarrel is operated.

A core tube assembly is carried nteriorly of and coaxially with thedrill barrel body 10 and consists of a thrust sub 17 supporting theassembly, a swivel joint and thrust bearing 184, an extensible couplinggenerally indicated at 19 and a core tube 20. r

The thrust sub 17 consists of a central body member with four radiallyextending arms 21 as best shown in Figs. 3 and 4, it beingl understoodthat the number of arms employed may be more or less at the option ofthe manufacturer. The outer ends of the arms 2l t in notches 22 formedin the upper edge of the sleeve 14 to prevent rotation of the thrustsub; and longitudinal movement of the sub is prevented as it is securelyheld between the drill barrel sub and the upper edge of the sleeve 14.

. A sleeve 23 is threadedly secured to the thrust sub 17 and dependsdownwardly therefrom having an inwardly extending annular shoulder 24 atits lower end. This shoulder 24 supports a thrust bearing which forms aswivel connection between the drill barrel body and the core assembly.This thrust bearing comprises thrust rings 25 and 26 and ball bearings27. An axial spindle 28 extends upwardly through the sleeve and a locknut 30 at its upper end so that its weight is supported by the thrustbearing and it a part of the extensible coupling 19. The coupling 19consists of a collar 32 threadedly con` nected to the spindle 2B andsecured against rotational movement thereon by means of a lock nut 33. Aslip collar 34 is mounted for sliding movement on the spindle 28 belowthe collar '32, and as shown in Fig. 2, is held against the co1- lar 32by means of stud bolts 35. The slip collar 34 is provided with adownwardly extending interiorly threaded sleeve-like extension 36 forthe reception of a sleeve 37 which is welded at its lower end to a coretube sub 38 which supports the c'ore tube 20 in a conventional manner.The core tube sub 38 is provided with the usual check valve 39 whichserves to prevent drilling uid from entering the core tube from theupper end thereof but permits escape of the fluid within the core tubeas the tube receives the core.

In the operation of the device as so far described, the entire unit islowered into the well from which a core is to be taken. The drill barrells rotated so that the teeth of the cutter head 12 cuts an annulargroove to produce a core. As the groove is cut, the entire device movesdownwardly and a trimmer shoe 40 xed to the lower end of the core tubetrims the outer wall-of the core before it is received by the tube, itbeing understood that the core tube does not rotate because of theprovision of the swivel joint in the core tube assembly.

The trimmer shoe 40 is tted with core retaining mechanism generallyindicated at 41 which serves the purpose of pinching off the core andretaining it within the core tube as the device is drawn from the well.This mechanism is fully described and claimed in a copending applicationentitled Core tube trimmer shoe, led June 7, 1933, Ser. No. 674,651.

The operation as above described is applicable to the position of thecore tube assembly illustrated in Fig. 2 of the drawing, which positionis employed when the core is being taken from solid formation.

When the formation from which the core is to be taken is soft or sandy,the device is used in the position shown in Fig. 1, in which positionthe stud bolts 35 have been removed, permitting the slip collar 34 toslide downwardly upon the spindle 28 until it abuts a thrust collar 42which limits its downward movement. As the slip collar 34 supports thecore tube through the sleeve 37 and sub 38, this downward movement`permits the core tube to move downwardly until the lower edge of thetrimmer shoe extends to a position in advance of the cutting edges ofthe teeth 13, as clearly illustrated in Fig. 1.

The weight of the core tube 20 and the frictional force of the drillingfluid which is being pumped downwardly through the drill barrel tolubricate the cutter head serve to maintain the core tube in thisdownward vposition and cause the trimmer shoe to be advanced into theformation prior to action upon the formation by the cutting teeth 13 andthe drilling fluid. Thus, the soft or sandy formation is received by thecore tube before it has been broken up and disrupted by the drillingoperation. Thus, by simply removing the stud bolts 35, the device may besub, a core .and thrustbearing and is nues with a nut 29 converted froma core extractor capable of operation in hard formations to a coreextractor that is particularly adapted to the removal of soft or sandycores.

When a core of the length desired has been extracted, the entire deviceis drawn from the well and in order to remove the core tube assemblyfrom within the drill barrel, it is merely necessary to remove the drillbarrel sub 15 from the sleeve 14, said members being threadedlyconnected as described above. After the sub 15 has been removed, thethrust sub may be grasped by an upwardly extending perforated boss 43and the entire core tube assembly drawn from within the drill barrelwhereupon the core is removed from the core tube in a conventionalmanner.

From the foregoing it will appear that the present invention provides arotary core barrel which through simple and novel mechanical means ismade adaptable to the recovery of cores from either soft or hardformations and in which the core tube assembly may be expedientlyremoved after the core has been extracted.

While we have shown the preferred form of our invention, it is to beunderstood that various changes may be made in its construction by thoseskilled inthe art without departing from the spirit of the invention asdefined in the appended claims.

Having thus described our invention, what we claim and desire to secureby Letters Patent is:

l. A core barrel comprising a drill barrel, a core tube in the drillbarrel, and a connection between the core tube and drill barrelcomprising a spindle supported axially of the drill barrel and free torotate relative thereto, a sliding collar on said spindle, meansconnecting the core tube to said collar vto permit movement of the coretube axiallyof the spindle, a pair of collars fixed to the spindle aboveand below said sliding collar to limit said movement, and means forsecuring said sliding collar to the uppermost of said fixed collars. l

2. A core barrel comprising a drill barrel, a core tube in the drillbarrel, and a connection between the core tube and drill barrelcomprising a spindle supported axially of the drill barrel and Afree torotate relative thereto, a sliding collar on said spindle, meansconnecting the core tube to said collar to permit movement of the coretube axially of the spindle, a pair of collars fixed to the spindleabove and below said sliding collar to linut said movement, and boltssecuring said sliding collar to the uppermost of said iixed collars toretain the core tube in a raised position relative to the drill barrel,said bolts being removable to permity the core tube to move to a lowerposition.

3. A core barrel comprising a drill barrel having notches formed in itsupper end, a thrust sub having radial extensions fitting in saidnotches, a spindle supported by said thrust sub and free to rotaterelative thereto, a swivel connection permitting relative rotation ofsaid spindle and tube, supported by said spindle, and an extensibleconnection between the core tube and spindle whereby the position of thecore tube may be varied axially of the spindle and drill barrel.

4. A core barrel comprising a drill barrel, a core tube suspended insaid drill barrel, means for supporting said core tube in the drillbarrel, said means comprising a sub having radially extending arms, theinner wall of the drill barrel being notched for the reception of saidarms to prevent turning movementI of the sub in the barrel, a spindlecarried by said sub and held from axial movement thereby, but rotatablein said sub, and an operating connection between said sub and said coretube.

5. A core barrel comprising a drill barrel, a core tube suspended insaid drill barrel, means for supporting said core tube in the drillbarrel, said means comprising a sub having radially extending arms, theinner wall of the drill barrel being notched for the reception o saidarms to prevent turning movement of the sub in the barrel, a spindlecarried by said sub and held from axial movement thereby, but rotatablein said sub, an operating connection between said sub and said coretube, said operating connection enabling the position of the core tubeto be axially adjusted on said sub.

